C033109016

International Journal of Engineering Science Invention
ISSN (Online): 2319 – 6734, ISSN (Print): 2319 – 6726
www.ijesi.org Volume 3 Issue 3ǁ March 2014 ǁ PP.09-16
www.ijesi.org 9 | Page
Evaluation of Status of Ph and Conductivity on Transfer and
Enrichment Factors of Soil and Vegetables of Some Agricultural
Areas of Kaduna Metropolis Nigeria
1
Mahmud Imam Mohammed , 2
W.L.O Jimoh
1
Department of Applied Science, College of Science and Technology, Kaduna Polytechnic
2
Department of Pure and Industrial Chemistry, Bayero University, Kano Nigeria.
ABSTRACT: In this research work soil and some vegetables were collected from various irrigation sites of
Kaduna metropolis and analyzed for PH and conductivity using Jenway PH and conductivity meter. Transfer
factor and enrichment factor of the vegetable (tomatoes,lettuce, cabbage and spinach) were also determined via
heavy metal (Cu, Zn, Pb,Fe and Cd) analysis with the aid of atomic absorption spectrophotometer. In the soil
analysis it was found most PH values were mostly acidic which ranges between 5.8 to 6.9 with the exception
of. from Unguwan Dosa and Kurmin mashi with pH of 8.27 and 8.50 respectively. Based on pH values obtained
in this work which were predominantly acid and this influence the conductivity to be within the normal range as
well as moderately saline, hence, transfer factors from soil to spinach, tomatoes, cabbage and lettuce were
mostly below 1 showing that heavy metals are accumulated in their edible portion (leaves) and were less
compared to that of the soil (that is, absorb small amount of metal from the soil.) while few samples had
concentrations above or equal to 1 (≥ 1). This indicates that, the concentration of heavy metal accumulated in
the vegetable were higher than that of the soil. EF was also found to be from the anthropogenic source of
contamination with very few samples were from natural source, that is EF values ranges between 0.5 and 1.5
indicates that the metal is entirely from crust materials or natural processes, whereas EF values greater than
1.5 suggest that the sources are more likely to be from the anthropogenic source. This is because absorption
and accumulation of heavy metals in plant tissue depend upon many factors such as moisture,organic matter,
conductivity, pH and nutrient availability
KEYWORDS: Heavy Metals, Soil, vegetable, PH meter, conductivity meter, Atomic Absorption
Spectrophotometer (AAS), kaduna Metropolis,Nigeria.
I. INTRODUCTION
Heavy metals are among the major contaminant of food supply and are considered as problem to the
environment (Zaidi et al, 2005). Heavy metals contamination may occur due to irrigation with contaminated
water, the addition of fertilizers, metal based pesticides, industrial emissions, transportation, harvesting process
and storage. Advancement in technology has lead to high levels of industrialization leading to the discharge of
effluent bearing heavy metals into our environment.Toxic element is one which has neither essential nor
beneficial effect but only negative effects on normal metabolic function even when present in only small
amount. When vegetable accumulates heavy metals at a proportion exceeding the tolerance limit and if
consumed by man or other animals, then the excess proportion of these metals from the vegetables tend to
accumulates gradually in animal tissues at a very high concentration where it becomes toxic and causes
varieties of illness e.g. brain damage, tumor cell, miscarriage etc.Heavy metals concentrations in soil are
associated with biological and geological cycles and are influenced by anthropogenic activities such as
agricultural practices, industrial activities and waste disposal methods (Eja et al., 2003, Zuluyah et al, 2004).
Contamination and consequent pollution of the environment by toxic heavy metals have become an issue of
global concern due to their sources, widespread distribution and multiple effects on the ecosystem (Nriagu,
1990). Heavy metals are generally present in agricultural soils at low levels. Due to their cumulative behaviour
and toxicity, however, they have a potential hazardous effect not only on crop plants but also on human health
(Das et al., 1997).Excessive amount of fertilizers are applied to crops, considering that they are reasonable
insurances against yield losses and their economic consequences. Fertilizers contain not only major elements
necessary for plant nutrient and growth but also trace metal impurities such as Cd, Pb, or Ni (Zhan and Shan
2001). The uptake of these heavy metals by plants especially leafy vegetables is an avenue of their entry into the
human food chain with harmful effects on health (Uwah et al., 2009).

Evaluation of Status of Ph and Conductivity…
Human beings are encourage to consume more vegetables and fruits, because they are good source of
vitamins, minerals, fibres and also beneficial to their health. However, these plants contain both essential and
toxic metals over a wide range of concentrations.The aim of this research work is to assess the effect
conductivity on the soil and also determine the level of some heavy metals absorb by some vegetables as well as
correlate the origin of such pollution due to human activities.
II. MATERIALS AND METHODS
Sample and Sampling:
Vegetables such as Spinach, Cabbage, Tomatoes and Lettuce samples were collected from twenty one
(21) different irrigation sites of the farmlands of the Kaduna metropolis where they were irrigated with water
from the river or pond which are sometimes contaminated. Soil samples were also randomly collected from the
farm where these vegetables were grown and irrigated with water. These samples were then stored in polythene
bags and taken to the laboratory and dried in an oven at 1050
c.The dried samples were ground with mortar and
pestle and sieved with 2mm sieve.
DESCRIPTION OF THE SAMPLING SITES
Soil samples for heavy metal determination were collected from twenty one (21) irrigation sites of the
Kaduna metropolis. These sites were Kabala (KBL), Danmani (DMN), Rigasa (RGS), Barnawa (BNW), Makera
(MKR), Kakuri (KKR), Badiko (BDK) Nasarawa (NAS, Malali (MAL), Kudenda (KUD), Kinkinau (KKN),
Kawo (KWO), Unguwan Rimi (URM), Unguwan Sanusi (UNS), Tudun Wada (TDW), Doka (DKA), Unguwan
Dosa (UDS), Kabala Costain (CTA), Kurmin Mashi (KMS) and Abakpa (ABK). In this research work soil
sample from Rigachikun (RCK) irrigation site was taken as control site.
Map of the Sampling points and the control

III. SITES

SAMPLE PREPARATION
Determination of PH and conductivity
20g of the ground soil samples was placed in a beaker. 100cm3
of distilled water was added to form
solution. The PH and conductivity of sample solutions were determined using 3305 Jenway pH meter and ELE
470 conductivity meter respectably. The PH and conductivity of the soil samples were taken and recorded.
Vegetable samples
5g of the ground Vegetable samples were ashed in a muffle furnace at a temperature of 5500
c for five
hours and digested with 20cm3
of HNO3/H2O2 (2:1). The digested residues were dissolved with 50cm of
distilled water and filtered in 50cm3
volumetric flask.
Soil samples:
20g of the finely ground soil samples was mixed with 60cm3
(5:5:1) H2SO4/HNO3/HCl acid mixtures
and the content were refluxed for 12 hours. The sample was washed with 1M HNO3 and 100cm3
of deionized
water was also added and centrifuged. The elements were determined using bulk scientific model VPG 210
model atomic absorption spectrophotometer (AAS).
In order to investigate the ratio of the concentration of heavy metal in a plant to the concentration heavy metal
in soil, the transfer factor was calculated based on the method described by Oyedele et al, 1995 and Harrison
and Chirgawi, 1989).
TF = Ps (µgg-1
/ St (µgg-1
)
Where Ps is the plant metal content originating from the soil and St is the total content in the soil.
The enrichment factor (EF) has been calculated to derive the degree of soil contamination and heavy metal
accumulation in soil and in plants growing on contaminated site with respect to soil and plants growing on
uncontaminated soil (Kisku et al., 2000).
According to Ergin et al., (1991) and Rubio et al., (2000) the metal enrichment factor (EF) is defined as follows:
background
Fe
M
sample
Fe
M
EF













Where M = Metal Concentration in soil sample and EF is the enrichment factor. (M/Fe)sample is the ratio of metal
and (M/Fe)background is the ratio of metals and Fe concentration of a background. The background concentrations
of metals were taken from an undisturbed area.
Five contamination categories are recognized on the basis of the enrichment factor as follows: (Sutherland 2000)
EF<2 is deficiency to minimal enrichment
EF<2-5 is moderate enrichment
EF<2-20 is significant enrichment
EF20-40 is very high enrichment
EF>40 is extremely high enrichment
IV. RESULTS AND DISCUSSION
Table 1.0: Mean pH and Conductivity in soil of different irrigation sites of Kaduna metropolis
Sampling Sites Mean pH
Mean conductivity
(µscm-1
)
SL (KBL) 6.5 ± 0.306 1.793 ± 0.301
SL (DMN) 6.4 ± 0.451 1.570 ± 0.044
SL (RGS) 6.0 ± 0.681 1.760 ± 0.052
SL (BNW) 6.4 ± 0.400 1.827 ± 0.237
SL (MKR) 6.2 ± 0.115 1.720 ± 0.017
SL (KKR) 6.6 ± 0.173 1.990 ± 0.060
SL (BDK) 6.3 ± 0.306 1.138 ± 0.844
SL (NAS) 5.9 ± 0.473 1.470 ± 0.070
SL (MAL) 6.2 ± 0.252 2.537 ± 0.474
SL (KUD) 6.5 ± 0.173 1.960 ± 0.442
SL (KKN) 5.9 ± 0.603 2.297 ± 0.614
SL (KWO) 5.8 ± 0.300 2.633 ± 0.754
SL (URM) 6.9 ± 1.710 2.260 ± 0.862
SL (UNS) 5.9 ± 0.404 2.343 ± 0.560
SL (TDW) 6.1 ± 0.557 2.453 ± 0.912

SL (DKA) 6.3 ± 0.473 1.723 ± 0.059
SL (UDS) 8.3 ± 0.208 1.610 ± 0.036
SL (CTA) 6.2 ± 0.473 2.110 ± 0.235
SL (KMS) 8.5 ± 0.400 1.723 ± 0.211
SL (ABK) 6.4 ± 0.400 1.620 ± 0.062
SL RCK (Control) 5.8 ± 0.681 2.643 ± 0.625
Table 1.0 shows the summary of mean pH and conductivity in soil from different irrigation sites.
Conductivity is a measurement of ability of conductor to convey electricity and is mainly due to dissolved
mineral matters as well as ionic solute. The magnitude of this, is a useful indication of the total concentration of
the ionic solute. That is higher the conductivity value of a given soil the more the concentration of ions present.
The above table also shows conductivity of the soil from the irrigation sites of Kaduna metropolis in which they
are all within the normal range as stated by Zaku et al., (2011). Boulding (1994) classified conductivity in soil
as: non saline when < 2; moderate saline when it is between 2 -8 ; very saline when it is between 8 – 16 ;
extremely saline if > 16. From the results of this study, most of the conductivity are moderately saline with few
being non saline. The amount of heavy metals mobilized in soil environment is a function of pH, properties of
metals, redox conditions, soil chemistry, organic matter content, clay content, cation exchange capacity and
other soil properties (Arun and Mukherjee, 1998; Kimberly and William, 1999; Sauve et al., 2000). The result
of metal analysis showed that, most of the sampling sites had high concentration of metals such lead and
cadmium evaluated in the soil and this account for high conductivity while others had moderate concentration of
metals such (Zn,Cu and Fe) analyzed in the soil and may account for low conductivity. Heavy metals are
generally more mobile at pH < 7 than at pH > 7.The pH of the soils from the irrigation sites of Kaduna
metropolis ranged 5.80 to 6.93.This is therefore hazardous for agricultural purposes since crops are known to
take up and accumulate heavy metals from contaminated soils in their edible portions (Wei et al.,) in contrast
with samples from Unguwan Dosa and Kurmin mashi with pH of 8.27 and 8.50 respectively.
Table 4: Mean for all the transfer factor(TF) for the whole vegetable in irrigation sites.
Table shows the transfer factor of heavy metals from soil to vegetables such as spinach,tomatoes,cabbage
and lettuce. For spinach samples, TF values were below 1 with the exception of samples from Kawo (2.45 for
Cd) and Tudun wada (1.00 for Cd), Unguwan dosa (1.00 for Cu), Abakpa (1.00 for Pb) and Rigachikun (1.11
for). For tomatoes samples are below 1 with the exception of samples from Rigasa (17.25 for Cd), Kakuri (1.01

for Cd), Kawo (1.56), Unguwan Sanusi (3.00), Tudunwada (1.60) , Doka (1.06), Abakpa (1.00 for both Cu and
Pb) and Rigachikun (control) (1.00 for Cu). All TF for cabbage samples are below 1 with the exception of
samples from Rigasa (18.25 for Cd), Kakuri (1.27 for Cd), Kawo (2.35 for Cd), Unguwan Sanusi (15.66 for Cd),
Tudunwada (2.95), Costain (1.00 for Cu) and Kurmi mashi (1.07 for Cu and 1.15 for Pb). For lettuce samples
are below 1 with the exception of samples from Rigasa (2.66 for Cd),Malali (1.01 for Cd, 1.03 for Fe and 1.17
for Cu),Kawo (1.48 for Cd) , Tudun wada(1.00 for Cd ),Doka (1.09 for Cd) and Rigachikun (control) 1.18 for
Cu.).In situation whereby the TF values were below 1 showing that heavy metals are accumulated in their edible
portion (leaves) are less compared to that of the soil (that is, absorb small amount of metal from the soil.)
Transfer factor is one of the key components of human exposure to metals through the food chain. Transfer
factors were computed for the heavy metal to quantify the relative differences in bioavailability of metals to
plants so as to identify the efficiency of a plant species to accumulate a given heavy metal. these factor were
based on the root uptake of the metals and discount the foliar absorption of atmospheric metal deposits
(Lokeshwari and Chandrapper,2006).Based on pH values obtained in this work which were predominantly acid
and this influence the conductivity to be within the normal range as well as moderately saline, hence, transfer
factors from soil to spinach, tomatoes, cabbage and lettuce in this research work were mostly below 1 showing
that heavy metal is accumulated in their edible portion (leaves) and were less compared to that of the soil (that
is, absorb small amount of metal from the soil.) while few samples had concentrations above or equal to 1 (≥ 1).
This indicates that, the concentration of heavy metal accumulated in the vegetable were higher than that of the
soil.
This is because absorption and accumulation of heavy metals in plant tissue depend upon many factors
such as moisture,organic matter, pH and nutrient availability (Sharma et al., 2004) so also the physiological
response of each plant do exerts control on the degree of bioaccumulation of different metal. Consequently,
metal mobility and plant availability are very important when assigning the effect of soil contamination on plant
metal uptake as well as translocation and toxicity or ultra structural alterations (Luo and Rammer,1995;Stresty
and Madhara ,1999; Chandra et al., 2001.). The mobility and bioavailability of trace elements in soil has been
increasing concern both in agricultural and environmental studies due to possible toxic effect of
bioaccumulation in plants and vertical leaching or transport into shallow ground water system. The mobility of
metal like zn increase with decreasing pH but in alkaline soils it could be mobile because of its ability to create
mineral – organic compound and complexes. Pb has a strong affinity for organic ligand and the formation of
such complexes may greatly increase the mobility of pb in soil. The acidic range of soil in this work was found
to increase the mobilization of heavy metals and as such increase their uptake.
Table 3.0 Enrichment factor of heavy metals in soil in irrigated farmland of Kaduna metropolis
Table3.0 shows enrichment factors for heavy metals such as Cd,Fe ,Zn ,Cu and Pb in soil. Cadmium from
Malali (1.6) and Unguwan Dosa (1.6 ) samples occurred with EF valued greater than 1.5 suggesting
anthropogenic. The enrichment factor for Zinc shows that samples from Malali (2.2) and Unguwan Dosa (2.0)
are moderatly enriched. Enrichment factors (EF) for copper showed that samples Barnawa (2.6), Malali (2.1)
and Unguwan Dosa (2.0) are moderately enriched and as such they are from anthropogenic source.
Sampling sites Elements
Cd Zn Cu Pb Fe
Kabala 0.5 0.9 0.5 0.5 1.11
Danmani 0.4 0.7 0.7 0.5 1.15
Rigasa 0.01 0.8 0.2 0.8 1.22
Barnawa 0.4 0.4 2.6 2.1 2.37
Makera 0.7 1.2 1.2 0.4 0.84
Kakuri 0.1 0.7 0.2 2.2 1.49
Badiko 0.5 0.7 0.6 0.3 1.51
Nasarawa 0.7 0.9 1.1 0.6 1.11
Malali 1.6 2.2 2.1 0.2 0.37
Kudenda 0.8 1.1 1.1 0.6 0.94
Kinkinau 0.3 1.0 1.1 0,6 0.97
Kawo 0.1 0.6 1.2 2.3 1.75
Unguwan Rimi ND 0.8 1.3 0.2 1.33
Unguwan sanusi 0.01 0.6 0.5 0.1 1.65
Tudun wada 0.1 0.5 1.5 0.3 1.98
Doka 0.3 0.5 1.2 2.4 1.99
Unguwan Dosa 1.6 2.0 2.0 1.3 0.51
Costain 0.9 1.2 0.9 0.5 0.84
Kurmin mashi 0.6 0.7 0.9 0.4 0.74
Abakpa 1.0 1.6 1.1 1.0 0.61

The table also showed enrichment factor for lead in which it has the following, Kakuri (2.2), Kawo
(2.3), Barnawa (2.1) and Doka (2.4) suggesting that they are from anthropogenic source.The EF for iron are
mostly from natural source. All these prediction were made in accordance with Zhang and Liu (2002) The
effect of conductivity of soil is also extended to their enrichment Factor, since enrichment factor (EF) is the
degree of soil contamination and heavy metal accumulation in soil and plants growing in such contaminated
site. In this research work it was found that the conductivity are within the normal range, moderately saline
while some are non saline, as a result of this EF was found to be from the anthropogenic source of
contamination with very few samples were from natural source as stated by Zhang and Liu (2002), that is EF
values ranges between 0.5 and 1.5 indicates that the metal is entirely from crust materials or natural processes,
whereas EF values greater than 1.5 suggest that the sources are more likely to be from the anthropogenic source.
Similar enrichment factor which was ascribed to the uptake of heavy metals by plant during their growth and
development. The rate of metal uptake by the plant, that is TF as well as EF could have been affected by other
factors such as plant age, plant species, soil pH ,nature of soil and climate. (Alloway and Ayres,1997)
V. CONCLUSION
From the result of the pH and metals analyzed in this work, some areas had moderate concentration of
metals as evaluated in the soil and may account for the low conductivity while others had high metal
concentration of metals with respect to their pH and hence account for high conductivity. Heavy metals are
generally more mobile at pH < 7 than at pH > 7.The pH of the soils from the irrigation sites of Kaduna
metropolis ranged 5.80 to 6.93. It has been established that transfer factor (TF) and enrichment factor (EF) have
strong relationship with one another. Since heavy metals accumulated in the soil and transfer to the vegetable
(plant) were either from natural source or from the human activities known as anthropogenic source as
revealed from the study of enrichment factor (EF). transfer factors from soil to spinach, tomatoes, cabbage and
lettuce in this research work were mostly below 1 showing that heavy metals were accumulated in their edible
portion (leaves) and were less compared to that of the soil (that is, absorb small amount of metal from the soil.)
while few samples had concentrations above or equal to 1 (≥ 1).In this research work it was found that the
conductivity are within the normal range, moderately saline while some are non saline, as a result of this EF, the
soils analyzed were found to be from the anthropogenic source of contamination with very few samples from
natural source
ACKNOWLEDGEMENT
The Authors were grateful to the management of Kaduna Polytechnic for using their laboratory, and equipment
in carrying out this research work.
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